Why They're Called "Intermodal" Containers

Because they are designed in such a way as to easily shift between different modes of transportation, that's why.

This particular container is being offloaded from a ship onto a truck which will take it to a temporary location inside the container yard, where it will remain until a trucking company comes to pick it up and take it away to deliver the contents. These containers are equally at home on ships, trucks, or trains.